A radiation imaging system capable of obtaining excellent image quality is provided. The radiation imaging system includes a detection unit (205) configured to include a plurality of pixels which are arranged in a matrix and which output pixel values by converting radial rays into charges and to output image information, driving control means (204) for causing the plurality of pixels to perform a resetting operation until a signal indicating irradiation with radial rays is supplied and to stop the resetting operation and perform an operation of accumulating charges when the signal indicating irradiation with radial rays is supplied, and for performing an operation of reading pixel values of the plurality of pixels after the irradiation with radial rays is terminated so as to output image information corresponding to the irradiation with radial rays, correction coefficient obtaining means (207) for calculating correction coefficients in accordance with the image information output from the detection unit, and image correction means (208) for correcting the image information output from the detection unit using the correction coefficients calculated by the correction coefficient obtaining means.
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1. A radiation imaging system comprising: a detection unit configured to include a plurality of pixels which are arranged in a matrix and which output pixel values by converting radial rays into charges and to output image information; driving control means for causing the plurality of pixels to perform a resetting operation until a signal indicating irradiation with radial rays is supplied and to stop the resetting operation and perform an operation of accumulating charges when the signal indicating irradiation with radial rays is supplied, and for performing an operation of reading pixel values of the plurality of pixels after the irradiation with radial rays is terminated so as to output image information corresponding to the irradiation with radial rays; correction coefficient obtaining means for calculating correction coefficients in accordance with the image information output from the detection unit; and image correction means for correcting the image information output from the detection unit using the correction coefficients calculated by the correction coefficient obtaining means, wherein the correction coefficient obtaining means sets a pair of a first pixel value of a pixel included in a row which has been subjected to the resetting operation after the irradiation with radial rays is started and a second pixel value of a pixel which is included in a row which has not been subjected to the resetting operation after the irradiation with radial rays is started and which is included in a column including the pixel having the first pixel value, and the correction coefficients are calculated using the pair of values which belong to different columns.
A radiation imaging system captures high-quality images using a matrix of pixels that convert radiation into electrical charges. The system resets these pixels until radiation exposure begins, then accumulates charge to generate pixel values. After radiation stops, pixel values are read, forming image data. Crucially, it calculates correction coefficients based on the image data to improve quality. This calculation uses pairs of pixel values: one from a row that *was* reset during radiation, and another from a row that *was not*, located in the same column. Correction coefficients are derived from multiple such pairs across different columns.
2. The radiation imaging system according to claim 1 , wherein the driving control means controls operation of the detection unit using a signal indicating irradiation with radial rays output from a radiation control apparatus which controls irradiation with radial rays.
The radiation imaging system, as described previously, controls the pixel operation using a signal from a radiation control apparatus. This apparatus manages the radiation emission itself, and the imaging system responds directly to the signals indicating when radiation is being emitted, dictating when pixel resetting stops and charge accumulation begins.
3. The radiation imaging system according to claim 1 , further comprising: detection means for detecting irradiation with radial rays and outputting a signal indicating the irradiation with radial rays, wherein the driving control means controls operation of the detection unit using the signal indicating irradiation with radial rays output from the detection means.
The radiation imaging system, as described previously, includes a radiation detector. This detector independently senses radiation exposure and generates a signal. Instead of relying on an external radiation control apparatus, the imaging system uses this internal detector's signal to manage pixel operation, specifically controlling when the pixel resetting stops and charge accumulation begins.
4. The radiation imaging system according to claim 1 , wherein the correction coefficient obtaining means sets a pair of a first average value obtained by averaging pixel values of a plurality of pixels included in a row which has been subjected to the resetting operation after the irradiation with radial rays is started and a second average value obtained by averaging pixel values of a plurality of pixels which are included in a row which has not been subjected to the resetting operation after the irradiation with radial rays is started and which are included in columns including the plurality of pixels used for generating the first average value, and the correction coefficients are calculated using a plurality of pairs of values included in different columns.
The radiation imaging system, as described previously, calculates correction coefficients using a modified approach. Instead of single pixel values, it averages pixel values across multiple pixels in a row. A "first average" comes from a row reset during radiation; a "second average" from a non-reset row in the same column(s). Correction coefficients are calculated from many such averaged pairs in different columns to improve image quality.
5. The radiation imaging system according to claim 1 , wherein the correction coefficient obtaining means calculates the correction coefficients using a least-square method.
The radiation imaging system, as described previously, calculates the correction coefficients using a least-squares method. This mathematical technique minimizes the difference between the original image data and the corrected image data, resulting in optimized correction coefficients.
6. The radiation imaging system according to claim 1 , wherein the correction coefficient obtaining means calculates the correction coefficients in accordance with a row number of a row where the resetting operation is stopped.
The radiation imaging system, as described previously, calculates correction coefficients based on the row number where the pixel resetting stopped. This row number is used as a key parameter in the correction coefficient calculation, allowing for row-specific adjustments to improve image quality.
7. The radiation imaging system according to claim 6 , wherein the correction coefficient obtaining means calculates the correction coefficients in accordance with the row number of the row where the resetting operation is stopped which is input by the driving control means.
The radiation imaging system, as described previously, calculates correction coefficients based on the row number where the pixel resetting stopped. This row number is provided by the driving control mechanism. The driving control mechanism provides the information for row identification to the correction coefficient calculator.
8. The radiation imaging system according to claim 6 , wherein the correction coefficient obtaining means calculates the correction coefficient in accordance with the row number of the row where the resetting operation is stopped which is calculated in accordance with the image information.
The radiation imaging system, as described previously, calculates correction coefficients based on the row number where the pixel resetting stopped. This row number is calculated based on image information which allows dynamic adjustment of correction coefficients based on the image itself.
9. The radiation imaging system according to claim 6 , wherein the first pixel value is a pixel value of a pixel included in the row where the resetting operation is stopped, and the second pixel value is a pixel value of a pixel included in a row immediately after the row where the resetting operation is stopped.
The radiation imaging system, as described previously, calculates correction coefficients. The "first pixel value" used in the calculation is from the row where resetting stopped. The "second pixel value" is from the *next* row immediately after the row where resetting stopped.
10. The radiation imaging system according to claim 6 , wherein the first pixel value is a pixel value of a pixel included in a row immediately before the row where the resetting operation is stopped, and the second pixel value is a pixel value of a pixel included in a row immediately after the row where the resetting operation is stopped.
The radiation imaging system, as described previously, calculates correction coefficients. The "first pixel value" used in the calculation is from the row immediately *before* the row where resetting stopped. The "second pixel value" is from the row immediately *after* the row where resetting stopped.
11. The radiation imaging system according to claim 1 , wherein the correction coefficients include an offset correction coefficient, a gain correction coefficient, and a width correction coefficient indicating a width of artifact generated in an image.
The radiation imaging system, as described previously, calculates correction coefficients that include three specific types: an offset correction, a gain correction, and a width correction. The width correction specifically addresses the width of artifacts appearing in the image, helping to remove or minimize these imperfections.
12. The radiation imaging system according to according to claim 1 , wherein the correction coefficients include an offset correction coefficient, a gain correction coefficient, and shape correction coefficient strings indicating amounts of artifact in individual rows generated in an image.
The radiation imaging system, as described previously, calculates correction coefficients which include an offset correction, a gain correction, and shape correction coefficient strings. These shape correction coefficient strings provide correction amounts for each individual row to remove artifacts within the generated image.
13. The radiation imaging system according to claim 11 , wherein the correction coefficient obtaining means calculates the width correction coefficient or the shape correction coefficient strings in accordance with the image information.
The radiation imaging system, as described previously, calculates width correction coefficients or shape correction coefficient strings (both related to artifact removal) based on the image information. This allows the system to dynamically adjust the artifact correction based on the content of the image itself.
14. The radiation imaging system according to claim 11 , wherein the correction coefficient obtaining means calculates the width correction coefficient or the shape correction coefficient strings in accordance with current supplied to a bias line of the pixels.
The radiation imaging system, as described previously, calculates width correction coefficients or shape correction coefficient strings (both related to artifact removal) based on the current supplied to a bias line of the pixels. This allows the system to adjust for changes in the bias line.
15. The radiation imaging system according to claim 1 , wherein the correction coefficient obtaining means removes, when the pair of values is abnormal, the abnormal pair of values before calculating the correction coefficients.
The radiation imaging system, as described previously, performs quality control on the pixel value pairs before calculating correction coefficients. If a pair is deemed "abnormal," it is removed from the calculation to prevent errors and improve the accuracy of the correction coefficients.
16. The radiation imaging system according to claim 15 , wherein the correction coefficient obtaining means determines that the pair of values is abnormal in a case where at least one of the pixel values in the pair of values is out of an amount of variation estimated from quantum noise relative to neighboring pixel values.
The radiation imaging system, as described previously, removes abnormal pixel value pairs before calculating correction coefficients. A pair is considered abnormal if either pixel value deviates excessively from neighboring pixels, exceeding the variation expected from quantum noise.
17. The radiation imaging system according to claim 15 , wherein the correction coefficient obtaining means determines that the pair of values is abnormal in a case where at least one of the pixel values in the pair of values is out of an amount of variation estimated from system noise relative to neighboring pixel values.
The radiation imaging system, as described previously, removes abnormal pixel value pairs before calculating correction coefficients. A pair is considered abnormal if either pixel value deviates excessively from neighboring pixels, exceeding the variation expected from system noise.
18. The radiation imaging system according to claim 15 , wherein the correction coefficient obtaining means determines that the pair of values is abnormal in a case where at least one of the pixel values in the pair of values is saturated.
The radiation imaging system, as described previously, removes abnormal pixel value pairs before calculating correction coefficients. A pair is considered abnormal if either pixel value is saturated (at its maximum possible value), indicating it's unreliable for accurate correction.
19. The radiation imaging system according to claim 15 , wherein the correction coefficient obtaining means determines that the pair of values is abnormal in a case where at least one of the pixel values in the pair of values is a negative value.
The radiation imaging system, as described previously, removes abnormal pixel value pairs before calculating correction coefficients. A pair is considered abnormal if either pixel value is negative, which is physically impossible and suggests an error.
20. The radiation imaging system according to claim 15 , wherein the correction coefficient obtaining means determines that the pair of values is abnormal in a case where at least one of the pixel values in the pair of values corresponds to a defective pixel.
The radiation imaging system, as described previously, removes abnormal pixel value pairs before calculating correction coefficients. A pair is considered abnormal if either pixel value comes from a known defective pixel, as this would skew the correction calculation.
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July 7, 2014
August 22, 2017
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